Field of the Invention
The present teachings are directed to methods to produce carbon nanotubes (hereinafter “CNTs”) on an appropriate substrate by thermal deposition of a catalyst metal precursors, for example, ferrocene, along with a carbon feedstock by chemical vapor deposition (hereinafter “CVD”) followed by growth of the CNTs.
Discussion of the Related Art
Hague et al. in U.S. Patent Appln. Pub. US 2011/0311427 A1 describe CNT arrays grown on carbon substrates including diamond, carbon foil and carbon fibers. A catalyst layer is deposited on a substrate and then coated with an insulating layer like alumina. This structure is then heated to activate the catalysts and crack the insulating layer. The structure with the activated catalysts and the cracked insulation are then exposed to CNT growth conditions.
Hague et al. also discuss in paragraph 0005 how direct growth of dense arrays of CNTs on a carbon surface, including diamond is not possible by conventional growth methods. Even though CVD methods were well known to Hague et al., there is no suggestion that their substrates would be applicable or desirable for CVD growth of CNTs.
There is a need for a method of growing vertically aligned CNTs on a carbon-based substrate via a CVD method utilizing catalyst components, such as ferrocene-based catalysts.